Magenta couplers are known to include 5-pyrazolones, indazolones, cyanoacetyls, chromans, pyrazoloazoles, etc. In particular, the skeletons of 5-pyrazolones and pyrazoloazoles among these couplers have been studied widely since the magenta colors formed therefrom have excellent absorption characteristics and high color image fastness and are highly practicable.
Among these 5-pyrazolones and pyrazoloazoles, those which are unsubstituted in the coupling position, or so-called 4-equivalent 5-pyrazolone couplers, have a specifically low coloring efficiency of 40 to 50%, the efficiency meaning the proportion of the molar amount of the dye as formed from 1 mol of the coupler. This means that double the molar amount or more of the coupler is required in order to obtain an equimolar amount of the dye therefrom, as compared with yellow, cyan or other couplers, and that large amounts of silver halides are also required. For this reason, the proposal of so-called 2-equivalent couplers where a group capable of being removed as an anion is introduced into the coupling active position of the 5-pyrazolone skeleton has been developed. This is because the coloring efficiency is improved up to 80 to 90% and the amount of the silver halide to be used is reduced by the introduction of the group which can be removed as an anion into the coupler. On these grounds, magenta couplers which are expected to be used in color photographic materials in view of the characteristic thereof and of the economical aspect are said to be 2-equivalent 5-pyrazolone couplers having an anion-removing group and pyrazoloazoles.
Regarding the 2-equivalent 5-pyrazolone couplers, examples of oxygen atom-removing couplers are described in U.S. Pat. Nos. 3,311,476, 3,419,391 and 4,146,396; examples of nitrogen atom-removing couplers are described in U.S. Pat. Nos. 4,367,282, 4,076,533 and 4,241,168; and examples of sulfur atom-removing couplers are described in U.S. Pat. Nos. 3,227,554, 4,407,936, 4,264,723 and 4,351,897. Regarding pyrazoloazole type couplers, examples thereof are described in U.S. Pat. Nos. 3,369,897, 3,725,067, 4,500,630 and 4,540,654 and Japanese Patent Application (OPI) Nos. 33552/85 and 43659/85 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application").
In silver halide color photographs, the occurrence of stains in the non-exposed parts is unfavorable, as whitening the color images, increasing the color turbidity thereof and deteriorating the visual sharpness thereof. Especially in the case of reflective materials (such as color papers), the reflected density of the stain is theoretically augmented to several times of the transmitted density and, therefore, even a weak stain is an extremely important factor in deteriorating the image quality.
The occurrence of the stains in the silver halide color photographs is principally classified into four types from the reasons thereof, as follows: The first results from the heat or moisture as imparted to the non-processed materials during the preservation thereof from the manufacture to the photographic treatment; the second results from the development fog of silver halides; the third results from the color stains of color couplers with development processing solutions (for example, aerial fog, etc.) or from the dyes as formed by the oxidation of the developing agents remaining in the emulsion films with oxygen in the bleaching bath or in air followed by the reaction of the thus oxidized product with couplers (for example, bleaching stain); and the fourth results from the variation of the photographic materials themselves, when exposed to light, moisture or heat after having been developed with the lapse of time. The stains resulting from the development of the 2-equivalent 5-pyrazolone couplers in the present invention are the third and fourth stains.
The development of color photographic materials has another difficult problem in that the development processing solution is not freshly prepared, in general, in every development processing step except in some unusual cases but, in practice, a development replenisher is added to the processing tank in accordance with the amount of the developer solution as used in each step. However, it is impossible to keep the composition of the processing solution constant only by supplementing the water lost in the development process.
More precisely, the development processing solutions comprise, in general, a color developer solution, a stopping solution, a bleaching solution or a bleaching-fixation solution (or a so-called blix solution), and these are used at a high treating temperature of 31.degree. C. to 43.degree. C. in the respective processing steps, whereupon the compositions of these processing solutions vary because the developing agent decomposes or is oxidized with air after being used for a long period of time, or the components as dissolved out from the photographic materials while being processed accumulate in the processing solutions, or the processing solutions as adhered to the photographic materials which are being processed are brought into the next bath together with the materials. In other words, the processing solutions in the actual processing of photographic materials are so-called running solutions. Under this situation, the replenishment of the shortage of the chemical agents or the recovery for the removal of any waste materials from the processing solutions is carried out in practice. However, this procedure is not sufficient.
In particular, stains occur very often in the photographic light-sensitive materials containing 2-equivalent 5-pyrazolone couplers or pyrazoloazole type couplers when processed with such running solutions, and the prevention of the occurrence of these stains by conventional technical means has been insufficient up to the present.
More precisely, in order to prevent such stains, a method has been known to be effective, where an alkyl hydroquinone (for example, as described in U.S. Pat. Nos. 3,935,016 and 3,960,570) is incorporated in a photographic material, especially in the emulsion layer thereof where the stain will occur. In addition, chromans and coumarans (e.g., as described in U.S. Pat. No. 2,360,290) and phenols (e.g., as described in Japanese Patent Application (OPI) No. 9449/76) are said to be effective in this way.
Further, U.S. Pat. Nos. 4,463,085 and 4,483,918 and Japanese Patent Application (OPI) Nos. 218445/84 and 229557/84 have proposed the effectiveness of certain kinds of amine compounds in this regard. However, all of these conventional compounds are still insufficient for attaining the object of the present invention.
Under the circumstances, the first object of the present invention is to prevent the stains which occur in the development of photographic light-sensitive materials containing a 2-equivalent pyrazolone coupler and/or a pyrazoloazole type coupler, and especially to completely prevent the stains which occur in the development thereof with a development processing solution in a running state.
The second object of the present invention is to provide photographic light-sensitive materials which contain a 2-equivalent pyrazolone coupler and/or a pyrazoloazole type coupler and a small amount of silver and which have a high sharpness and a good developability.
It is to be noted that Japanese Patent Application (OPI) No. 211147/82 describes the use of 3-pyrazolidone derivatives for the prevention of stains. These 3-pyrazolidone compounds are, however, quite different from the compounds to be used in the present invention, since they have a substituent on the 2-nitrogen atom.
In this connection, the incorporation of a 3-pyrazolidone derivatives, especially the precursor thereof, in silver halide photographic materials is claimed in some patents. For instance, U.S. Pat. No. 3,241,967 claims the use of 2-(substituted methyl)-3-pyrazolidones, which are, however, quite different from the compounds as used in the present invention. The pyrazolidones have neither the object nor the effect of the present invention. Japanese Patent Application (OPI) Nos. 40245/82 and 104641/84 describe 3-pyrazolidone precursor compounds where the 3-enol is protected with an acyl ester or carbonate ester. In these publications, however, the object for the addition of the compounds to silver halide photographic materials is to impart good photographic sensitivity, maximum density and desired sensitometry characteristics to the materials, and the technical means as illustrated in Japanese Patent Application (OPI) No. 40245/82 is one to be adopted to black-and-white photographic materials. On the other hand, the technical means as illustrated in the above-mentioned Japanese Patent Application (OPI) No. 104641/84 is to attain high sensitivity of the photographic materials without the increment of the fog density thereof. Thus, the object of this technical means is different from that of the present invention, although the technical scope of this publication includes the case of color photographic materials. Further, this publication describes only 4-equivalent 5-pyrazolone couplers, and the object of the use of these couplers is different from the object of the present invention where 2-equivalent 5-pyrazolones are used.
Japanese Patent Application (OPI) No. 85749/81 describes the use of nondiffusible 1-phenyl-3-pyrazolidones in order to improve the stability of 4-alkylthio-5-pyrazolone type couplers, which is, however, different from the object of the present invention. In addition, the use of such nondiffusible pyrazolidone compounds could not attain the object of the present invention.